A Rare Presentation of Acute Immune Thrombocytopenia, Refractory to First Line Therapy, Despite Euthyroid State

ITP is an autoimmune hematologic disorder characterized by immune mediated destruction of platelets. Up to 90% of patients experience disease self-limited to 6 months (2, 3). The majority of patients' platelet counts increase with steroid and/or intravenous immunoglobulin (IVIG) treatment, to prevent complications, within 24-72 hours. (2, 3). ITP may occur in otherwise healthy children or coincide with other autoimmune disorders, such as Hashimoto's thyroiditis. Previous case reports suggest that induction of a euthyroid state with levothyroxine improved patients' platelet response to IVIG and steroids (1). We report the case of a 15 year old female diagnosed with acute ITP, also found to have Hashimoto's thyroiditis, whose ITP proved refractory to first line therapy, despite achieving a euthyroid state on levothyroxine treatment.

A 15 year old female presented complaining of prolonged menstrual bleeding and easy bruising, associated with fatigue, for 3 weeks. The patient had a gradually enlarging thyroid gland. Review of systems was otherwise negative and family history was non-contributory. On physical exam, vital signs demonstrated weight at the 97th percentile and tachycardia. The patient had palmar and conjunctival pallor. There was firm, non-tender thyromegaly, without palpable nodules. She had yellow and purple, circular, 3 cm ecchymoses on her right anterior inner thigh and left upper abdominal quadrant. Neurological, cardiovascular, pulmonary, and gastrointestinal exams were otherwise normal.

Initial laboratory evaluation demonstrated a microcytic anemia with hemoglobin of 5.3 g/dl, mean corpuscular volume of 76.3 fL, reticulocyte count of 3.2%, and platelet count of 5 x 10³/μL, with few large platelets seen on peripheral smear. Peripheral blood flow cytometry proved negative for leukemia and lymphoma. Evaluation for other causes of thrombocytopenia, including infection and familial thrombocytopenia, was negative. She had a normal absolute neutrophil count and a negative direct Coomb's test, ruling out Evan's syndrome. Her thyroid studies suggested hypothyroidism, with a thyroid stimulating hormone (TSH) of 233.40 μ[IU]/mL, free T4 of 0.3 ng/dL, thyroglobulin antibody >1000 [IU]/mL, and thyroid peroxidase antibody >900 [IU]/mL. Neck ultrasound revealed an enlarged, heterogeneous thyroid gland with multiple, small, echogenic, non-shadowing nodules, consistent with Hashimoto's thyroiditis.

During the hospital course, the patient received supportive care with 2 courses of IVIG and packed red blood cells (pRBCs). Her hemoglobin improved to 8.7 g/dL, and her platelets reached 34 x 10³/μL, prior to discharge. Initially her TSH was 233 μ[IU]/mL, which decreased to 87 μ[IU]/mL after inpatient treatment with 88 mcg of levothyroxine daily. She continued on a steroid taper over 21 days.

She continued to experience persistent symptoms of thrombocytopenia and microcytic anemia. She required a second hospitalization for prolonged epistaxis and menorrhagia due to thrombocytopenia, with a platelet count of 2 x 10³/μL, while on steroid therapy. Due to refractory response to steroids and IVIG, despite treatment for hypothyroidism, hematology initiated second line treatment with oral eltrombopag. Her goiter did not decrease in size, but the patient's TSH stabilized at 4.51 μ[IU]/mL and free T4 at 0.9 ng/dL. She improved her platelet count to 209 x 10³/μL, within 2 weeks of therapy with eltrombopag, and she remained asymptomatic. The adolescent physician also began oral contraceptive pills for menstrual regulation. Since the patient's platelet count improved significantly, hematology decreased her dose of eltrombopag, and the patient maintained a platelet count between 200-400 x 10³/μL.

This is a rare pediatric case of coexisting ITP and Hashimoto's thyroiditis, in which thrombocytopenia did not improve with first line therapy for ITP, despite the achievement of a euthyroid state with levothyroxine. She initially responded with a transient, minimal improvement in her platelet count, requiring an early decision to initiate second-line management. Second-line therapy is usually reserved for patients with chronic ITP (thrombocytopenia greater than 6 months). Based on our patient's response, we would suggest use of eltrombopag in acute ITP patients who are refractory to first line therapy.